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CERIOPORID^. 
species of Sparsicavea, which seem, however, to be Petaloporidae, 
as they have maculse and not mesopores. 
The Cretaceous Bryozoa of this group are easily divisible into 
those which are monomorphic, of which Ceriopora is a convenient 
type, and those which are dimorphic ; the latter include Heteropora 
and its allies, with irregularly arranged zooecia, and Radiopora and 
its allies, in which the zooecia are radially arranged. 
CEllIOPOBID^. 
Synonymy. 
Cerioporina, pars, von Hagenow, 1851. 
Cavidce, pars, d’Orbigny, 1854. 
Gerioporidce , pars, Marsson, 1887 ; pars, Ulrich, 1900. 
Cerioporidce, Hennig, 1894. 
Frondiporidce, pars. Vine, 1885. 
Amplexoporidm, pars, Gregory, 1896. 
Diagnosis. 
Trepostomata with prismatic or sub-cylindrical zooecia. No 
mesopores. Zooecia thin -walled. Diaphragms absent or 
present and sometimes numerous. Zoarium typically massive, 
but it may be composed of thick branches. (Age, Mesozoic 
and Cainozoic.) 
Affinities. 
In the Catalogue of the Jurassic Bryozoa (p. 195) a series of 
species of Ceriopora was included in the Palaeozoic family the 
Amplexoporidae, owing to the absence of any definite character, 
except age, to separate them from that family. I am still unable 
to point to any definite separation between the Amplexoporids 
of the Lower and Middle Palaeozoic and the Mesozoic Cerioporids; 
but the two groups are widely separated in time, and I cannot 
see any evidence to show that various Jurassic and Cretaceous 
Cerioporids have descended from different Palaeozoic Amplexo- 
porids. The probabilities seem to be that all the Jurassic and 
Cretaceous Cerioporids are the offspring of a small Triassic fauna, 
which was probably monogenetic from either a Triassic or Dpper 
Palmozoic ancestor. Hence it seems most convenient and natural 
to separate the Mesozoic and Palaeozoic forms into distinct 
families. 
Of the names available for the family, d’Orbigny’ s Cavidae 
would be better retained, if retained at all, for Ceriocava (of which 
